Apparatus For Controlling the Consistency of a Flow of Stock Solution

ABSTRACT

An apparatus is disclosed for controlling the consistency of a flow of stock solution flowing from a header to a slice lip of a headbox of a papermaking machine so that the cross machine direction consistency profile of a resultant web is controlled. The apparatus includes a flow channel which is disposed within the headbox between the header and the slice lip. The flow channel has an upstream and a downstream end such that the flow of the stock solution is in a flow direction from the upstream end towards the downstream end of the flow channel. The flow channel includes a primary channel having a first and a second extremity such that the flow of the stock solution is through the primary channel from the first extremity to the second extremity of the primary channel. A supply channel has a first and a second end and is disposed downstream relative to the primary channel for the flow therethrough of a supply portion of the flow of the stock solution. The second end of the supply channel is connected to the slice lip so that the supply portion of the flow of the stock solution flows to the slice lip. A recirculation channel has a first and a second termination, the recirculation channel being disposed downstream relative to the primary channel for the flow therethrough of a recirculation portion of the flow of the stock solution. The second termination of the recirculation channel is connected to the header so that the recirculation portion of the flow of the stock solution flows to the header. A generator is disposed adjacent to the primary channel for generating ultrasonic waves within the flow of the stock solution flowing through the primary channel. The ultrasonic waves move fiber particles suspended within the stock solution for controlling the consistency of the stock solution flowing through the primary channel. Also, an ultrasound absorber is disposed adjacent to the primary channel such that the flow of the stock solution flows in the flow direction within a region disposed between the generator and the absorber so that in operation of the apparatus, when the stock solution is flowing within the region, the fiber particles suspended within the stock solution are deviated from the flow direction. The arrangement is such that the consistency of the stock solution flowing from the primary channel through the supply channel is different from the consistency of the stock solution flowing from the primary channel through the recirculation channel so that the consistency of the supply portion of the stock solution flowing through the slice lip is controlled thereby controlling the cross machine direction consistency profile of the resultant web.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for controlling theconsistency of a flow of stock solution flowing from a header to a slicelip of a headbox of a papermaking machine. More specifically, thepresent invention relates to an apparatus and a method for controllingthe consistency of a flow of stock solution flowing from a header to aslice lip of a headbox of a papermaking machine so that the crossmachine direction profile of a resultant web is controlled.

2. Background Information

In the papermaking industry, a solution of paper stock is supplied to aheadbox of a papermaking machine. The pressurized stock is guidedthrough a plurality of headbox flow channels into a slice chamber of theheadbox. The stock is then ejected as a thin ribbon through a slice lipdefined by the downstream end of the headbox. The ejected stock isreceived onto a moving Fourdrinier screen where water drains from thestock solution to provide a formed web.

One of the more important quality parameters in the paper making processis the evenness of the cross machine direction basis weight profile.Even if the cross machine profile of the concentration of the stockejected from the headbox slice is fairly even, the final basis weightprofile is normally altered due to several defects produced along theprocess in the machine. These defects include an uneven flow profile ofthe stock ejected from the headbox, uneven retention of the fibers onthe fourdrinier, uneven pick up of solids in the size press or in thecoating station. The usual way to control the aforementioned defects isto compensate for them by controlling the consistency profile of thestock before it is ejected from the headbox.

The headbox is divided into several discrete cross machine sections of acertain width and in each of these sections the consistency of the stockis individually controlled according to the measure of the basis weightof the final sheet in the corresponding cross machine section.

The present invention provides an apparatus and method for controllingthe consistency profile in a headbox and for providing a web having amore uniform cross machine direction basis weight profile.

Many prior art arrangements have been devised in an attempt to provide arelatively uniform grammage or basis weight in a cross machine directionof the web. Early attempts at controlling the aforementionedcharacteristic of the web included the provision of a plurality of slicelip screw jacks spaced a few inches from each other in a cross machinedirection. Such jacks were connected to a movable slice lip of the sliceopening. Controlled movement of the jacks would warp the slice lip insuch a way that a relatively uniform ribbon of stock would be ejectedthrough the slice opening. Nevertheless, such arrangements were complex.Also, the adjustment of one of the jacks had the tendency to alter thebasis weight of stock flowing past an adjacent jack.

A further development included the provision of uniformly spaced slicelips while controlling the consistency or dilution of the stock in across machine direction upstream relative to the slice lips. Moreparticularly, immediately upstream from the tube bank, a flow ofdiluting white water or the like was selectively introduced into one ormore of the headbox tubes of the tube bank so that the consistency ofthe stock flowing through that particular tube would be changed ordiluted relative to the consistency of stock flowing through an adjacenttube.

More particularly, in the prior art dilution arrangement, by controllingthe injected suspension flow in the vicinity of the tube bank, it waspossible to a large extent to control the concentration of the resultantsuspension downstream from the injection point. Such an injectionarrangement has the disadvantage that the correction of suspensionconcentration requires the adding of an extraneous means to thesuspension itself which can generate technological problems into thepaper making process. Such an arrangement also necessitates theprovision of additional circuitry for the dilution water and theprovision of additional pumping apparatus. The need of the addition of asecondary suspension to control the concentration of the main suspensionmakes it almost impossible to selectively change the suspended particleswithout interacting with the hosting liquid phase.

The present invention provides a unique means for achieving a uniformbasis weight or grammage in a cross machine direction by the applicationof ultrasonic waves for controlling in a cross machine direction, thegrammage of the resultant web.

According to the present invention, when ultrasonic waves are applied toa liquid suspension, such ultrasonic waves have the capability of movingthe suspended particles. In particular, particles suspended in astationary suspension and contained within a reservoir are located inbetween an ultrasound generator and a ultrasound absorber device. Whenultrasonic waves are applied to the particles, such particles are movedby the ultrasound waves in a direction extending from the generator tothe absorber.

Similarly, the same effect occurs when ultrasonic waves are applied to amoving suspension of particles. For example, when a flow of thesuspension is moving in a generic direction at a generic speed and thesuspension flow crosses a region between the ultrasound generator andthe absorber, then the suspended particles will be deviated from theflow direction by a motion component which is parallel to the line goingfrom the generator to the absorber.

The result is that downstream from the ultrasonic device, the suspensionwill not have the same homogeneity as the homogeneity of the suspensionupstream relative to the ultrasonic device. This is so because thesuspended particles will tend to migrate toward the absorber. As aconsequence of such migration downstream from the ultrasonic device, thesuspension flow will have been concentrated on the absorber side anddiluted on the generator side.

The object of the present invention is the application of theaforementioned physical principle to control the concentration of apaper making fibrous material suspension or stock solution through ahead box.

In a paper machine head box, according to the present invention, thecontrol of fiber suspension concentration or consistency in any specificcross machine section of the headbox is used to control the final papersheet cross machine grammage profile.

Applying the above-mentioned effect of ultrasonic waves on fluidsuspensions in a specific cross machine section of the headbox by theuse of an ultrasonic device dedicated that specific headbox crossmachine section, it is possible to exert a force on any single solidparticle suspended in the region corresponding to the same specificcross machine section of the headbox and move it inside the liquidhosting phase. As a consequence, it is possible to locally concentrateor dilute the suspension. More specifically, by applying energy in theform of ultrasound waves, it is possible to create a degree ofdis-homogeneity into the suspension. By controlling the amount of energysupplied to the generator, or the capacity of the absorber, it ispossible to control the state of dis-homogeneity of the suspension inthe specific section and as a consequence, to control localconcentration of the suspension.

As an example, in the system of the present invention, the effect isapplied to a suspension such as paper stock flowing into a channel fromleft to right.

Ultrasound waves cross the channel from the top to the bottom. Suchwaves push suspended particles or fibers toward the bottom side of thechannel. Downstream from the ultrasonic device, the channel is splitinto secondary channels, that is a supply channel and a recirculationchannel. It is evident that the average concentration of the suspensionreceived by the supply channel is in this case lower than the averageconcentration of the suspension received by the recirculation channel.The difference between the two concentrations is in some way related tothe power delivered by the ultrasonic device. In particular, the higherthe power, of the generator or the capacity of the absorber, the biggeris the difference in concentration between the supply channel and therecirculation channel. By controlling the ultrasonic device, it ispossible to control the concentration in at least one of the twosecondary channels.

By controlling the power delivered by the ultrasonic device, it ispossible to control the concentration in at least one of the twosecondary channels.

In a paper machine headbox according to the present invention, the fibersuspension of the stock solution enters the headbox from a supply headerand is transferred to a tube bank through a bank of flow channels. Theadjacent channels forming the flow channels can be either physicallyseparated one from the other by sidewalls or not. The principle of twosecondary channels is applied to each single flow channel. Each flowchannel is equipped with its own ultrasonic device. Also, eachultrasonic device includes an independent control. Each flow channel issplit into two secondary channels, one top channel and one bottomchannel. One of the two secondary channels is a supply channel of acorresponding cross machine direction section of the headbox tube bank.The other secondary channel or recirculation channel of each flowchannel permits recirculation to the supply system of the headbox. Arecirculation header collects the flow from each of the recirculationchannels of all the flow channels. The stock collected by therecirculation header is simply recirculated into the stock approachsystem with no need for any extra equipment.

Applying the principle of the present invention, it is evident that itis possible to individually control the concentration of the suspensionin any secondary supply channel covering a specific respective headboxcross machine section by controlling its respective ultrasonicgenerator. From previous knowledge of paper machine technology, it isknown that if one is able to control independently the stockconcentration into each specific cross machine section of a headbox,then it is possible to control the cross machine grammage profile of thefinished paper.

Therefore, it is a primary feature of the present invention to providean apparatus and method for controlling the cross machine consistencyprofile of a stock solution within a headbox of a papermaking machinethat overcomes the problems associated with the prior art arrangements.

Another feature of the present invention is the provision of anapparatus for controlling the cross machine consistency profile of astock solution within a headbox of a papermaking machine so that thegrammage profile of the resultant web can be controlled.

Other features and advantages of the present invention will be readilyapparent to those skilled in the art by a consideration of the detaileddescription of a preferred embodiment of the present invention containedherein.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus for controlling the crossmachine consistency profile of a flow of stock solution flowing from aheader to a slice lip of a headbox of a papermaking machine so that thecross machine direction consistency profile of a resultant web iscontrolled. The apparatus includes a flow channel which is disposedwithin the headbox between the header and the slice lip. The flowchannel has an upstream and a downstream end such that the flow of thestock solution is in a flow direction from the upstream end towards thedownstream end of the flow channel. The flow channel includes a primarychannel having a first and a second extremity such that the flow of thestock solution is through the primary channel from the first extremityto the second extremity of the primary channel. A supply channel has afirst and a second end and is disposed downstream relative to theprimary channel for the flow therethrough of a supply portion of theflow of the stock solution. The second end of the supply channel isconnected to the slice lip so that the supply portion of the flow of thestock solution flows to the slice lip. A recirculation channel has afirst and a second termination, the recirculation channel being disposeddownstream relative to the primary channel for the flow therethrough ofa recirculation portion of the flow of the stock solution. The secondtermination of the recirculation channel is connected to the header sothat the recirculation portion of the flow of the stock solution flowsto the header. A generator is disposed adjacent to the primary channelfor generating ultrasonic waves within the flow of the stock solutionflowing through the primary channel. The ultrasonic waves move fiberparticles suspended within the stock solution for controlling theconsistency of the stock solution flowing through the primary channel.Also, an ultrasound absorber is disposed adjacent to the primary channelsuch that the flow of the stock solution flows in the flow directionwithin a region disposed between the generator and the absorber so thatin operation of the apparatus, when the stock solution is flowing withinthe region, the fiber particles suspended within the stock solution aredeviated from the flow direction. The arrangement is such that theconsistency of the stock solution flowing from the primary channelthrough the supply channel is different from the consistency of thestock solution flowing from the primary channel through therecirculation channel so that the consistency of the supply portion ofthe stock solution flowing through the slice lip is controlled therebycontrolling the cross machine direction profile of the resultant web.

In a more specific embodiment of the present invention, the apparatusincludes a further generator which is disposed adjacent to the primarychannel and laterally relative to the generator for generatingultrasonic waves within the flow of the stock solution flowing throughthe primary channel. The ultrasonic waves move fiber particles suspendedwithin the stock solution for controlling the consistency of the stocksolution flowing through the primary channel.

Furthermore, a further ultrasound absorber is disposed adjacent to theprimary channel and laterally relative o the absorber such that the flowof the stock solution flows in the flow direction within a furtherregion disposed between the further generator and the further absorbersuch that in operation of the apparatus, when the stock solution isflowing within the further region, the fiber particles suspended withinthe stock solution are deviated from the flow direction so that theconsistency of the stock solution flowing from the primary channeldownstream from the further region through the supply channel isdifferent from the consistency of the stock solution flowing from theprimary channel downstream from the further region through therecirculation channel. The arrangement is such that the consistency of afurther supply portion of the stock solution flowing through the slicelip downstream from the further region is controlled relative to thesupply portion of the stock solution flowing downstream from the regionthrough the slice lip thereby controlling the cross machine directionconsistency profile of the resultant web.

In a preferred embodiment of the present invention, the flow directionis approximately parallel to a direction from the header to the slicelip.

Also, the primary channel defines a primary conduit of rectangular crosssectional configuration, the primary conduit extending from the firstextremity to the second extremity of the primary channel.

More particularly, the first end of the supply channel extends from thesecond extremity of the primary channel and the supply channel isdisposed above the recirculation channel.

However, in another embodiment of the present invention, the supplychannel is disposed below the recirculation channel.

Additionally, the first termination of the recirculation channel extendsfrom the second extremity of the primary channel such that the flow ofthe stock solution flowing through the primary channel is split into thesupply portion and the recirculation portion adjacent to the secondextremity of the primary channel.

In one embodiment of the present invention, the apparatus furtherincludes a control device which is electrically connected to thegenerator for controllably altering the generation of the ultrasonicwaves by the generator.

However, in an alternative embodiment of the present invention, a deviceis mechanically connected to the generator for controllably altering alocation of the generator relative to the primary channel so thatgeneration of the ultrasonic waves within the region by the generator isaltered.

In another embodiment of the present invention, a controller iselectrically connected to the ultrasound absorber for controllablyaltering absorption of the ultrasonic waves by the absorber.

Alternatively, a control device is mechanically connected to theabsorber for controllably altering a disposition of the absorberrelative to the primary channel so that absorption of the ultrasonicwaves by the absorber is altered.

In each of the alternative embodiments of the present invention, theflow direction within the region is disposed non parallel to a directionfrom the generator to the absorber.

However, more specifically, the flow direction within the region isdisposed substantially normal to a direction from the generator to theabsorber.

Moreover, the direction from the generator to the absorber issubstantially normal to the flow direction within the region such thatin use of the apparatus, the ultrasonic waves deviate movement of thefiber particles in a component direction which is disposed angularlybetween the flow direction and the direction from the generator to theabsorber.

The present invention also includes a method for controlling theconsistency of a flow of stock solution flowing from a header to a slicelip of a headbox of a papermaking machine so that the cross machinedirection consistency profile of a resultant web is controlled. Themethod includes the steps of guiding the flow of the stock solutionthrough a flow channel which is disposed within the headbox between theheader and the slice lip. The flow channel includes a primary channelwhich has a first and a second extremity. A supply channel has a firstand a second end, the supply channel being disposed downstream relativeto the primary channel for the flow therethrough of a supply portion ofthe flow of the stock solution. The second end of the supply channel isconnected to the slice lip so that the supply portion of the flow of thestock solution flows to the slice lip. A recirculation channel has afirst and a second termination, the recirculation channel being disposeddownstream relative to the primary channel for the flow therethrough ofa recirculation portion of the flow of the stock solution. The secondtermination of the recirculation channel is connected to the header sothat the recirculation portion of the flow of the stock solution flowsto the header.

The method also includes the steps of generating ultrasonic waves withinthe flow of the stock solution flowing through the primary channel by anultrasonic generator. The ultrasonic waves move fiber particlessuspended within the stock solution for controlling the consistency ofthe stock solution flowing through the primary channel.

Additionally, the method includes absorbing the ultrasonic waves by anultrasound absorber disposed adjacent to the primary channel such thatthe flow of the stock solution flows in the flow direction within aregion which is disposed between the generator and the absorber. Thearrangement is such that when the stock solution is flowing within theregion, the fiber particles suspended within the stock solution aredeviated from the flow direction so that the consistency of the stocksolution flowing from the primary channel through the supply channel isdifferent from the consistency of the stock solution flowing from theprimary channel through the recirculation channel. The method is suchthat that the consistency of the supply portion of the stock solutionflowing through the slice lip is controlled thereby controlling thecross machine direction consistency profile of the resultant web.

Many modifications and variations of the present invention will bereadily apparent to those skilled in the art by a consideration of thedetailed description contained hereinafter taken in conjunction with theannexed drawings which show a preferred embodiment of the presentinvention. However, such modifications and variations fall within thespirit and scope of the present invention as defined by the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic to demonstrate the effect of the application ofultrasonic waves on a stock solution according to the present invention;

FIG. 2 is a similar view to that shown in FIG. 1 but shows the generatorenergized;

FIG. 3 is a similar view to that shown in FIG. 2 but shows the fibersuspension or stock solution in motion;

FIG. 4 is a diagrammatic representation of an apparatus according to thepresent invention for controlling the consistency of stock solutionwithin a headbox of a papermaking machine;

FIG. 5 a side elevational view of an apparatus for controlling theconsistency of a flow of stock solution flowing from a header to a slicelip of a headbox of a papermaking machine;

FIG. 6 is a sectional view taken on the line 6-6 of FIG. 5;

FIG. 7 is a similar view to that shown in FIG. 6 but shows anotherembodiment of the present invention;

FIG. 8 is a sectional view taken on the line 8-8 of FIG. 7;

FIG. 9 is a side elevational view of another embodiment of the presentinvention;

FIG. 10 is a similar view to that shown in FIG. 6 but shows a furtherembodiment of the present invention;

FIG. 11 is a similar view to that shown in FIG. 10 but shows a furtherembodiment of the present invention;

FIG. 12 is a similar view to that shown in FIG. 10 but shows anotherembodiment of the present invention; and

FIG. 13 is a similar view to that shown in FIG. 11 but shows a furtherembodiment of the present invention.

Similar reference characters refer to similar parts throughout thevarious views and embodiments of the drawings.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic to demonstrate the effect of the application ofultrasonic waves on a stock solution according to the present invention.As shown in FIG. 1, a generator 10 is disposed adjacent to a first sideof a container 16 and an absorber 24 is disposed on the opposite side ofthe container 16. The container 16 is filled with a suspension of fiberparticles 18, 19 and 20 randomly dispersed throughout the host liquidsuch as water.

FIG. 2 is a similar view to that shown in FIG. 1. However, as shown inFIG. 2, the generator 10 is energized so that the generator 10 emitsultrasonic waves 12, 13 and 14 through the container 16 containing thefiber particles 18, 19 and 20 suspended in water. Accordingly, theultrasonic waves 12-14 cause the particles 18-20 to move through thewater in a direction as indicated by the arrow 22 from the generator 10towards the absorber 24.

FIG. 3 is a similar view to that shown in FIG. 2 but shows the fibersuspension or stock solution in motion. As shown in FIG. 3, the stocksolution which includes the fibers 18-20 is moving through the container16 in a flow direction as indicated by the arrow 26. As shown in FIG. 3,the flow direction 26 is normal to the direction 22. In this case, thefiber particles 18-20 will move in a component direction which isindicated by the arrow 28. The component direction 28 is disposedangularly between the directions 22 and 26. Consequently, in adownstream location relative to the generator 10, the suspension orstock solution will be more concentrated or will have a higherconsistency on the side 30 of the container 16 nearest to the absorber24. Similarly, the stock solution will be diluted or will be of a lowerconsistency on a further side 32 of the container 16 nearest to thegenerator 10 as shown in FIG. 3.

FIG. 4 is a diagrammatic representation of an apparatus according to thepresent invention for controlling the consistency of the stock solution34 which includes the fibers 18-20, within a headbox generallydesignated 36 of a papermaking machine. As shown in FIG. 4, when thegenerator 10 is activated, ultrasonic waves 12-14 are emitted throughthe stock solution 34 flowing in the flow direction 26 through theheadbox 36. The ultrasonic waves 12-14 move in the direction 22 from thegenerator 10 across the flow direction 26 of the stock solution 34towards the absorber 24. Consequently, the consistency or concentrationof the fibers within the stock solution 34 is greater on the side 30 ofthe headbox 36 which is nearest to the absorber 24. Such concentratedstock is diverted through a downstream recirculation channel 38.However, on the further side 32 of the headbox 36 nearest to thegenerator 10, the stock solution 34 is diluted because many of thefibers 18-20 have migrated towards the side 30 under the influence ofthe applied ultrasonic waves 12-14. Such diluted stock is guided througha downstream supply channel 40.

FIG. 5 a side elevational view of an apparatus generally designated 42according to the present invention for controlling the consistency of aflow of stock solution flowing from a header 44 to a slice lip 46 of aheadbox generally designated 36 of a papermaking machine so that thecross machine direction consistency profile of a resultant web iscontrolled. The apparatus 42 includes a flow channel generallydesignated 48 which is disposed within the headbox 36 between the header44 and the slice lip 46. The flow channel 48 has an upstream and adownstream end 50 and 52 respectively such that the flow of the stocksolution is in a flow direction 26 from the upstream end 50 towards thedownstream end 52 of the flow channel 48. The flow channel 48 includes aprimary channel 56 having a first and a second extremity 58 and 60respectively such that the flow of the stock solution is through theprimary channel 56 from the first extremity 58 to the second extremity60 of the primary channel 56. A supply channel 40 has a first and asecond end 64 and 66 respectively and is disposed downstream relative tothe primary channel 56 for the flow therethrough of a supply portion asindicated by the arrow 68 of the flow of the stock solution. The secondend 66 of the supply channel 40 is connected to the slice lip 46 so thatthe supply portion 68 of the flow of the stock solution flows to theslice lip 46. A recirculation channel 38 has a first and a secondtermination 72 and 74 respectively, the recirculation channel 38 beingdisposed downstream relative to the primary channel 56 for the flowtherethrough of a recirculation portion as indicated by the arrow 76 ofthe flow of the stock solution. The second termination 74 of therecirculation channel 38 is connected to the header 44 so that therecirculation portion 76 of the flow of the stock solution flows to theheader 44. A generator 10 is disposed adjacent to the primary channel 56for generating ultrasonic waves 12-14 within the flow of the stocksolution flowing through the primary channel 56. The ultrasonic waves12-14 move fiber particles 18-20 suspended within the stock solution forcontrolling the consistency of the stock solution flowing through theprimary channel 56. Also, an ultrasound absorber 24 is disposed adjacentto the primary channel 56 such that the flow of the stock solution flowsin the flow direction 26 within a region R disposed between thegenerator 10 and the absorber 24 so that in operation of the apparatus42, when the stock solution is flowing within the region R, the fiberparticles 18-20 suspended within the stock solution are deviated asindicated by the arrow 28 from the flow direction 26. The arrangement issuch that the consistency of the stock solution flowing from the primarychannel 56 through the supply channel 40 is different from theconsistency of the stock solution flowing from the primary channel 56through the recirculation channel 38 so that the consistency of thesupply portion 68 of the stock solution flowing through the slice lip 46is controlled thereby controlling the cross machine directionconsistency profile of the resultant web.

FIG. 6 is a sectional view taken on the line 6-6 of FIG. 5. As shown inFIG. 6, the flow channel 48 extends across most of the cross machinewidth of the headbox 36. Also, the supply channel 40 is shown leading tothe slice lip. Furthermore, the recirculation channel 38 is shown forreturning concentrated stock solution to the header.

FIG. 7 is a similar view to that shown in FIG. 6 but shows anotherembodiment of the present invention. As shown in FIG. 7, an apparatus 42a includes a further generator 84 disposed adjacent to the primarychannel 56 for generating ultrasonic waves within the flow of the stocksolution flowing through the primary channel 56. The ultrasonic wavesmove fiber particles suspended within the stock solution for controllingthe consistency of the stock solution flowing through the primarychannel 56.

FIG. 8 is a sectional view taken on the line 8-8 of FIG. 7. As shown inFIGS. 7 and 8, a further ultrasound absorber 86 is disposed adjacent tothe primary channel 56 such that the flow of the stock solution flows inthe flow direction 26 within a further region r disposed between thefurther generator 84 and the further absorber 86. The arrangements isstructured such that in operation of the apparatus 42 a, when the stocksolution is flowing within the further region r, the fiber particlessuspended within the stock solution are deviated from the flow direction26 so that the consistency of the stock solution flowing from theprimary channel 56 through the supply channel 62 downstream from theregion r is different from the consistency of the stock solution flowingfrom the primary channel 56 downstream from the region r through therecirculation channel 38. The arrangement is such that the consistencyof a further supply portion 88 of the stock solution flowing downstreamfrom the region r through the slice lip 46 is controlled relative to thesupply portion 68 of the stock solution as shown in FIG. 5, flowingdownstream from the region R through the slice lip 46 therebycontrolling the cross machine direction consistency profile of theresultant web.

In a preferred embodiment of the present invention, the flow direction26 is approximately parallel to a direction as indicated by the arrow116 from the header 44 to the slice lip 46.

Also, as shown in FIG. 5, the primary channel 56 defines a primaryconduit 118 of rectangular cross sectional configuration. As shown inFIG. 6, the primary conduit 118 extends from the first extremity 58 tothe second extremity 60 of the primary channel 56.

More particularly, as shown in FIG. 5, the first end of the supplychannel 40 extends from the second extremity 60 of the primary channel56 and the supply channel 40 is disposed above the recirculation channel38.

FIG. 9 is a side elevational view of another embodiment of the presentinvention. As shown in FIG. 9, the supply channel 40 b is disposed belowthe recirculation channel 38 b.

Additionally, as shown in FIG. 5, the first termination 72 of therecirculation channel 38 extends from the second extremity 60 of theprimary channel 56 such that the flow of the stock solution flowingthrough the primary channel 56 is split into the supply portion 68 andthe recirculation portion 76 adjacent to the second extremity 60 of theprimary channel 56.

FIG. 10 is a similar view to that shown in FIG. 6 but shows a furtherembodiment of the present invention. As shown in FIG. 10, the apparatusfurther includes a control device 120 which is electrically connected tothe generator 10 c for controllably altering the generation of theultrasonic waves by the generator 10 c.

FIG. 11 is a similar view to that shown in FIG. 10 but shows a furtherembodiment of the present invention. As shown in FIG. 11, a device 122such as a hydraulic or a pneumatic ram is mechanically connected to thegenerator 10 d for controllably altering a location of the generator 10d relative to the primary channel 56 as indicated by the arrow 123 sothat generation of the ultrasonic waves within the region R by thegenerator 10 d is altered.

FIG. 12 is a similar view to that shown in FIG. 10 but shows a furtherembodiment of the present invention. As shown in FIG. 12, a controller124 is electrically connected to the ultrasound absorber 24 e forcontrollably altering absorption of the ultrasonic waves by the absorber24 e.

FIG. 13 is a similar view to that shown in FIG. 11 but shows a furtherembodiment of the present invention. As shown in FIG. 13, a controldevice 126 such as a hydraulic or pneumatic ram is mechanicallyconnected to the absorber 24 f for controllably altering a dispositionof the absorber 24 f relative to the primary channel 56 as indicated bythe arrow 127 so that absorption of the ultrasonic waves by the absorber24 f is altered.

In each of the alternative embodiments of the present invention, theflow direction 26 within the region R and r is disposed non parallel toa direction 22 from the generator 10 to the absorber 24.

However, more specifically, the flow direction 26 within the region R isdisposed substantially normal to the direction 22 from the generator 10to the absorber 24.

Moreover, the direction 22 from the generator 10 to the absorber 24 issubstantially normal to the flow direction 26 within the region R suchthat in use of the apparatus, the ultrasonic waves deviate movement ofthe fiber particles in a component direction 28 shown in FIG. 5 which isdisposed angularly between the flow direction 26 and the direction 22from the generator 10 to the absorber 24.

The present invention also includes a method for controlling the crossmachine consistency profile of a flow of stock solution flowing from aheader 44 to a slice lip 46 of a headbox 36 of a papermaking machine sothat the cross machine direction profile of a resultant web iscontrolled. The method includes the steps of guiding the flow of thestock solution through a flow channel 48 which is disposed within theheadbox 36 between the header 44 and the slice lip 46. The flow channel48 includes a primary channel 56 which has a first and a secondextremity 58 and 60. A supply channel 40 has a first and a second end 64and 66, the supply channel 40 being disposed downstream relative to theprimary channel 56 for the flow therethrough of a supply portion 68 ofthe flow of the stock solution. The second end 66 of the supply channel40 is connected to the slice lip 46 so that the supply portion 68 of theflow of the stock solution flows to the slice lip 46. A recirculationchannel 38 has a first and a second termination 72 and 74, therecirculation channel 38 being disposed downstream relative to theprimary channel 56 for the flow therethrough of a recirculation portion76 of the flow of the stock solution. The second termination 74 of therecirculation channel 38 is connected to the header 44 so that therecirculation portion 76 of the flow of the stock solution flows to theheader 44.

The method also includes the steps of generating ultrasonic waves withinthe flow of the stock solution flowing through the primary channel 56 byan ultrasonic generator 10. The ultrasonic waves move fiber particlessuspended within the stock solution for controlling the consistency ofthe stock solution flowing through the primary channel 56.

Additionally, the method includes absorbing the ultrasonic waves by anultrasound absorber 24 disposed adjacent to the primary channel 56 suchthat the flow of the stock solution flows in the flow direction 26within a region R which is disposed between the generator 10 and theabsorber 24. The arrangement is such that when the stock solution isflowing within the region R, the fiber particles suspended within thestock solution are deviated from the flow direction 26 so that theconsistency of the stock solution flowing from the primary channel 56through the supply channel 40 is different from the consistency of thestock solution flowing from the primary channel 56 through therecirculation channel 38. The method is such that that the consistencyof the supply portion 68 of the stock solution flowing through the slicelip 46 is controlled thereby controlling the cross machine directionconsistency profile of the resultant web.

In operation of the apparatus according to the present invention, astock solution is supplied to the header under pressure. The stock flowsthrough the flow channel 48 so that when the generator and absorber 10and 24 respectively are activated, diluted stock flows from the region Rthrough the downstream supply channel 40 to the slice lip 46. However,in a lateral disposition in a cross machine direction as shown in FIG.8, the further generator and further absorber 84 and 86 respectively actupon the region r which is disposed laterally relative to the region Ras shown in FIG. 7. Consequently, the dilution of the stock flowingdownstream from the region r through the supply channel 40 can becontrolled or altered relative to the dilution of the laterally disposedflow of stock flowing downstream from the region R. In this manner, bythe provision a number of generators and corresponding absorbers, thecross machine directional consistency profile of the resultant web canbe controlled. Such control can be achieved as shown in FIGS. 10-13 byeither controlling the electrical supply to the generator or to theabsorber or by mechanically moving the disposition of the generator orthe absorber or both the generator and the absorber relative to theprimary channel 56.

According to the present invention, the generation capacity of thegenerator can be changed by increasing or decreasing the electricalinput or by moving the generator towards or away from the primarychannel.

Similarly, the absorption factor of the absorber can be changed byincreasing or decreasing the electrical input to the absorber or bymoving the absorber towards or away from the primary channel. Anycombination of the above can be used for controlling the ultrasonicwaves within the primary channel.

By altering the power to all of the generators such as 10 and 84 and/orthe corresponding absorbers 24 and 86 to the same power level would havea similar effect to altering the grammage valve on a conventionalheadbox. Typically, in a conventional headbox, when the grammage valveis altered, there would be a delay of two minutes before such changewould take effect downstream on the grammage of the resultant web.

One of the advantages of the arrangement according to the presentinvention when using an electrical control for the generator and/orabsorber is that the consistency control is accomplished by entirely anelectrical device rather than a mechanical device in the case of slicelip control.

Although the present invention describes the recirculation portion ofthe stock as returning to the header, it will be apparent to thoseskilled in the art that in fact, the recirculation portion will usuallybe returned to the header via the stock supply silo.

The present invention provides a unique apparatus and method forcontrolling the cross machine direction profile of a web.

1. An apparatus for controlling the consistency of a flow of stock solution flowing from a header to a slice lip of a headbox of a papermaking machine so that the cross machine direction consistency profile of a resultant web is controlled, said apparatus comprising: a flow channel disposed within the headbox between the header and the slice lip, said flow channel having an upstream and a downstream end such that the flow of the stock solution is in a flow direction from said upstream end towards said downstream end of said flow channel; said flow channel including: a primary channel having a first and a second extremity such that the flow of the stock solution is through said primary channel from said first extremity to said second extremity of said primary channel; a supply channel having a first and a second end, said supply channel being disposed downstream relative to said primary channel for the flow therethrough of a supply portion of the flow of the stock solution; said second end of said supply channel being connected to the slice lip so that said supply portion of the flow of the stock solution flows to the slice lip; a recirculation channel having a first and a second termination, said recirculation channel being disposed downstream relative to said primary channel for the flow therethrough of a recirculation portion of the flow of the stock solution; said second termination of said recirculation channel being connected to the header so that said recirculation portion of the flow of the stock solution flows to the header; a generator disposed adjacent to said primary channel for generating ultrasonic waves within the flow of the stock solution flowing through said primary channel, said ultrasonic waves moving fiber particles suspended within the stock solution for controlling the consistency of the stock solution flowing through said primary channel; and an ultrasound absorber disposed adjacent to said primary channel such that the flow of the stock solution flows in said flow direction within a region disposed between said generator and said absorber so that in operation of said apparatus, when the stock solution is flowing within said region, said fiber particles suspended within the stock solution are deviated from said flow direction so that the consistency of the stock solution flowing from said primary channel through said supply channel is different from the consistency of the stock solution flowing from said primary channel through said recirculation channel so that the consistency of said supply portion of the stock solution flowing through the slice lip is controlled thereby controlling the cross machine direction consistency profile of the resultant web.
 2. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 1 including: a further generator disposed adjacent to said primary channel and laterally relative to said generator for generating ultrasonic waves within the flow of the stock solution flowing through said primary channel, said ultrasonic waves moving fiber particles suspended within the stock solution for controlling the cross machine direction consistency profile of the stock solution flowing through said primary channel; a further ultrasound absorber disposed adjacent to said primary channel such that the flow of the stock solution flows in said flow direction within a further region disposed between said further generator and said further absorber such that in operation of said apparatus, when the stock solution is flowing within said further region, said fiber particles suspended within the stock solution are deviated from said flow direction so that the consistency of the stock solution flowing from said primary channel downstream from said further region through said supply channel is different from the consistency of the stock solution flowing from said primary channel downstream from said further region through said recirculation channel so that the consistency of a further supply portion of the stock solution flowing through the slice lip downstream from said further region is controlled relative to said supply portion of the stock solution flowing downstream from said region through the slice lip thereby controlling the cross machine direction profile of the resultant web.
 3. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 1 wherein said flow direction is approximately parallel to a direction from the header to the slice lip
 4. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 1 wherein said primary channel defines a primary conduit of rectangular cross sectional configuration, said primary conduit extending from said first extremity to said second extremity of said primary channel.
 5. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 1 wherein said first end of said supply channel extends from said second extremity of said primary channel.
 6. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 1 wherein said supply channel is disposed above said recirculation channel.
 7. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 1 wherein said supply channel is disposed below said recirculation channel.
 8. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 1 wherein said first termination of said recirculation channel extends from said second extremity of said primary channel such that the flow of the stock solution flowing through said primary channel is split into said supply portion and said recirculation portion adjacent to said second extremity of said primary channel.
 9. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 1 further including: a control device electrically connected to said generator for controllably altering generation of said ultrasonic waves by said generator.
 10. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 1 further including: a device mechanically connected to said generator for controllably altering a location of said generator relative to said primary channel so that generation of said ultrasonic waves within said region by said generator is altered.
 11. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 1 further including: a controller electrically connected to said ultrasound absorber for controllably altering absorption of said ultrasonic waves by said absorber.
 12. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 1 further including: a control device mechanically connected to said absorber for controllably altering a disposition of said absorber relative to said primary channel so that absorption of said ultrasonic waves by said absorber is altered.
 13. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 1 wherein said flow direction within said region is disposed non parallel to a direction from said generator to said absorber.
 14. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 1 wherein said flow direction within said region is disposed substantially normal to a direction from said generator to said absorber.
 15. An apparatus for controlling the consistency of a flow of stock solution as set forth in claim 14 wherein said direction from said generator to said absorber is substantially normal to said flow direction within said region such that in use of said apparatus, said ultrasonic waves deviate movement of said fiber particles in a component direction which is disposed angularly between said flow direction and said direction from said generator to said absorber.
 16. A method for controlling the consistency of a flow of stock solution flowing from a header to a slice lip of a headbox of a papermaking machine so that the cross machine direction consistency profile of a resultant web is controlled, said method comprising the steps of: guiding the flow of the stock solution through a flow channel which is disposed within the headbox between the header and the slice lip, the flow channel including: a primary channel having a first and a second extremity; a supply channel having a first and a second end, the supply channel being disposed downstream relative to the primary channel for the flow therethrough of a supply portion of the flow of the stock solution, the second end of the supply channel being connected to the slice lip so that the supply portion of the flow of the stock solution flows to the slice lip; a recirculation channel having a first and a second termination, the recirculation channel being disposed downstream relative to the primary channel for the flow therethrough of a recirculation portion of the flow of the stock solution, the second termination of the recirculation channel being connected to the header so that the recirculation portion of the flow of the stock solution flows to the header; generating ultrasonic waves within the flow of the stock solution flowing through the primary channel by an ultrasonic generator, the ultrasonic waves moving fiber particles suspended within the stock solution for controlling the consistency of the stock solution flowing through the primary channel; and absorbing the ultrasonic waves by an ultrasound absorber disposed adjacent to the primary channel such that the flow of the stock solution flows in the flow direction within a region disposed between the generator and the absorber such that when the stock solution is flowing within the region, the fiber particles suspended within the stock solution are deviated from the flow direction so that the consistency of the stock solution flowing from the primary channel through the supply channel is different from the consistency of the stock solution flowing from the primary channel through the recirculation channel so that the consistency of the supply portion of the stock solution flowing through the slice lip is controlled thereby controlling the cross machine direction consistency profile of the resultant web.
 17. An apparatus for controlling the consistency of a flow of stock solution flowing from a header to a slice lip of a headbox of a papermaking machine so that the cross machine direction consistency profile of a resultant web is controlled, said apparatus comprising: a flow channel disposed within the headbox between the header and the slice lip, said flow channel having an upstream and a downstream end such that the flow of the stock solution is in a flow direction from said upstream end towards said downstream end of said flow channel; said flow channel including: a primary channel having a first and a second extremity such that the flow of the stock solution is through said primary channel from said first extremity to said second extremity of said primary channel; a supply channel having a first and a second end, said supply channel being disposed downstream relative to said primary channel for the flow therethrough of a supply portion of the flow of the stock solution; said second end of said supply channel being connected to the slice lip so that said supply portion of the flow of the stock solution flows to the slice lip; a recirculation channel having a first and a second termination, said recirculation channel being disposed downstream relative to said primary channel for the flow therethrough of a recirculation portion of the flow of the stock solution; said second termination of said recirculation channel being connected to the header so that said recirculation portion of the flow of the stock solution flows to the header; a generator disposed adjacent to said primary channel for generating ultrasonic waves within the flow of the stock solution flowing through said primary channel, said ultrasonic waves moving fiber particles suspended within the stock solution for controlling the consistency of the stock solution flowing through said primary channel; an ultrasound absorber disposed adjacent to said primary channel such that the flow of the stock solution flows in said flow direction within a region disposed between said generator and said absorber so that in operation of said apparatus, when the stock solution is flowing within said region, said fiber particles suspended within the stock solution are deviated from said flow direction so that the consistency of the stock solution flowing from said primary channel through said supply channel is different from the consistency of the stock solution flowing from said primary channel through said recirculation channel so that the consistency of said supply portion of the stock solution flowing through the slice lip is controlled thereby controlling the cross machine direction consistency profile of the resultant web; a further generator disposed adjacent to said primary channel and laterally relative to said generator for generating ultrasonic waves within the flow of the stock solution flowing through said primary channel, said ultrasonic waves moving fiber particles suspended within the stock solution for controlling the consistency of the stock solution flowing through said primary channel; a further ultrasound absorber disposed adjacent to said primary channel and laterally relative to said absorber such that the flow of the stock solution flows in said flow direction within a further region disposed between said further generator and said further absorber such that in operation of said apparatus, when the stock solution is flowing within said further region, said fiber particles suspended within the stock solution are deviated from said flow direction so that the consistency of the stock solution flowing from said primary channel downstream from said further region through said supply channel is different from the consistency of the stock solution flowing from said primary channel downstream from said further region through said recirculation channel so that the consistency of a further supply portion of the stock solution flowing through the slice lip downstream from said further region is controlled relative to said supply portion of the stock solution flowing downstream from said region through the slice lip thereby controlling the cross machine direction consistency profile of the resultant web; said flow direction being approximately parallel to a direction from the header to the slice lip; said primary channel defining a primary conduit of rectangular cross sectional configuration, said primary conduit extending from said first extremity to said second extremity of said primary channel; said first end of said supply channel extending from said second extremity of said primary channel; said supply channel being disposed above said recirculation channel; said first termination of said recirculation channel extending from said second extremity of said primary channel such that the flow of the stock solution flowing through said primary channel is split into said supply portion and said recirculation portion adjacent to said second extremity of said primary channel; and said direction from said generator to said absorber being substantially normal to said flow direction within said region and said further region such that in use of said apparatus, said ultrasonic waves deviate movement of said fiber particles in a component direction which is disposed angularly between said flow direction and said direction from said generator to said absorber. 